textproduct: Rapid City

KEY MESSAGES

- Hot through the weekend with elevated to near critical fire weather conditions.

- Chance for isolated to scattered thunderstorms this afternoon and overnight, mainly across the Black Hills and parts of northeast Wyoming. Increasing chance of storms on Saturday.

- Slightly cooler conditions finally look to return for next week.

UPDATE

Issued at 941 PM MDT Fri Jul 17 2026

Haze and wildfire smoke will continue to filter over the area as sfc high slides southward and low level northeast flow persists. This has introduced some uncertainty as to highs for tomorrow as the smoke may lower temperatures somewhat. However, even if temperatures are "slightly" cooler, we'll still see highs in the 90s across much of our plains and northeastern WY zones. Sunday still promises to be hot as southerly return flow brings hot air back into the region. We could see temperatures exceeding 100 across much of the area. Making no changes to the ongoing Heat Advisory.

CAMs show elevated convection developing over northeastern WY into northwestern SD overnight tonight. Not expecting any severe weather with this activity overnight. Ridge riding shortwave crosses our area Saturday with enough monsoon moisture to support afternoon storms, mainly across the northeastern WY, the Black Hills into southwestern and south central SD where narrow band of ML CAPE of 1000-2000 J/kg is expected to form. Weak mid to upper level flow and subsequent lack of deep layer shear will limit any widespread severe potential but we could see a few "pulse-y" storms in the afternoon. A few storms could become strong with small hail and gusty winds.

DISCUSSION

(This Evening Through Friday) Issued at 207 PM MDT Fri Jul 17 2026

Strong upper ridging persists across the western CONUS. Water vapor imagery show several shortwaves riding the top of the ridge, resulting in storms across Idaho and western MT/WY. Surface obs show a cold front this morning has now sagged southward and stalled just south of I-90. South of the front temps are in the mid to upper 90s with dewpoints in the upper 40s to lower 50s. North of the front across NW SD temps have been much cooler than expected...temps in the 80s but with dewpoints in the mid to upper 60s, making it hazy and muggy. KUDX radar shows isolated storms have formed across the Black Hills along a N/S dryline over the central Black Hills. NAM has a good handle on dewpoints across the Black Hills, suggesting SBCAPE of 1800 J/kg. Shear is virtually non-existent, so storms will be pulsy and slow-moving in nature, which is what has been observed so far. Storms could have occasional small hail and heavy rain, as PWATs are 125-150% of normal. Storms will dissipate early this evening. Models are showing a shortwave crossing the northern Rockies continuing eastward overnight. This will bring increasing H70 moisture supporting elevated overnight convection from NE WY and NW SD...perhaps grazing the northern Black Hills. MUCAPE up to 1200 J/kg will be possible, but with very weak shear, severe weather is not expected. Overnight warm air advection will bring back hot temperatures to the CWA on Saturday...with highs in the upper 90s to lower 100s. Dewpoints will initially be in the 60s, bringing another muggy morning, but then dewpoints are expected to drop as the lower atmosphere mixes out in the mid to late morning. CAMS are showing an upper wave crossing the CWA late Saturday, bringing a round of afternoon/evening storms. There is uncertainty as to when Saturday storms will develop...with some models showing hardly any precip while others (CAMs) showing late afternoon convection over NE WY and the Black Hills. These storms then move eastward toward central SD overnight into early Sunday morning. MLCAPE of 1000-1500 J/kg and moderate shear may allow some storms to be strong with hail and gusty winds. Hot weather continues into Sunday with highs in the lower 100s. Then a cold front sometime late Sunday or Monday will finally bring temperature relief for the first half of next week (highs in the 80s/lower 90s).

AVIATION

(For the 06Z TAFS Through 06Z Saturday Night) Issued At 1004 PM MDT Fri Jul 17 2026

VFR conditions are expected through the TAF period.

Some elevated showers and isolated storms are possible overnight tonight in NE WY and NW SD which could cause localized gusty winds. And more storms are possible tomorrow in and near the Black Hills in the heat of the day before fading out in the evening.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM MDT /10 PM CDT/ Sunday for SDZ001-002- 012>014-025>027-030>032-041>044-046-047-049-072>078. WY...Heat Advisory until 9 PM MDT Sunday for WYZ054>056-058>060.